title: Crystal structure and function of C-terminal Sau3AI domain.
abstract: Sau3AI is a type II restriction enzyme that recognizes the 5'-GATC-3' sequence in double-strand DNA and cleaves at 5' to the G residue. The C-terminal domain of Sau3AI (Sau3AI-C), which contains amino acids from 233 to 489, was crystallized and its structure was solved by using the Multi-wavelength Anomalous Diffraction method. The Sau3AI-C structure at 1.9 A resolution is similar to the structure of MutH, a DNA mismatch repair protein that shares high sequence similarity with the N-terminal Sau3AI domain. The functional analysis shows that Sau3AI-C can bind DNA with one recognition sequence but has no cleavage activity. These results indicate that Sau3AI is a pseudo-dimer belonging to the type IIe restriction enzymes and the Sau3AI-C is the allosteric effector domain that assists DNA binding and cleavage.
authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Xu
authors.forename: Feng
authors.initials: F
authors.lastname: Yu
authors.forename: Si-Jie
authors.initials: SJ
authors.lastname: Xu
authors.forename: Yu
authors.initials: Y
authors.lastname: Ding
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Sun
authors.forename: Lin
authors.initials: L
authors.lastname: Tang
authors.forename: Xiao-Jian
authors.initials: XJ
authors.lastname: Hu
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Zhang
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: He
mesh_terms: D000595:Amino Acid Sequence; D020137:Base Pair Mismatch; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D015252:Deoxyribonucleases, Type II Site-Specific; C024405:GATC-specific type II deoxyribonucleases